Process of producing multilayer color negatives containing masking images for color correction purposes



Patented Apr. 21, 1953 PROCESS OF PRODUCING MULTILAYER COLOR NEGATIVES CONTAINING MASKING IMAGES FOR COLOR COR- RECTION PURPOSES Harold C. Harsh and Joseph S. Friedman, Binghamton, N. Y., assignors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application October 16, 1946, Serial No. 703,480

This invention relates to color photography, and more particularly to a process of producing multilayer color negatives containing masking images for color correction purposes.

In the production of color prints from multilayer color negatives, the color negative consists of yellow, magenta, and cyan images in the different layers. The cyan image represents the red, the magenta image the green, and the yellow image the blue record of the original subject. Color positive prints or transparencies may be obtained from such color negatives by direct printing onto a multi-layer color positive film or paper, or by making color separation negatives which are used for making the color positive prints. These color negatives do not as a rule, completely satisfy the spectral requirements for trichromatic color reproduction. For instance, the magenta colored image, formed by the imposition of green light upon the green sensitive layer, records the green densities. This image should transmit the blue and the red primaries, completely. To the extent to which it absorbs blue light, it superimposes a pattern of the green densities upon the blue, with consequent color falsification. This color falsiflcation makes itself manifest when the color negative is to be printed. That part of the exposure which is due to blue light, and which should form a record only of the image in the yellow layer in the negative, forms a record of the yellow image admixed with the record of the magenta. The image in the blue sensitive part of the copy material is, therefore, very impure, and serious color degradation results.

It is possible to overcome this defect if procedures are devised to register a pattern of the magenta dye image, equal in intensity to the degree to which the magenta dye absorbs blue light, but opposite in character, with the yellow dye images. In a similar manner the cyan dye image can be corrected for its blue absorption. These procedures produce masks or modifyin images which can be yellow in color, as suggested by the prior art, o they can be a neutral gray, composed of dye or silver.

Numerous methods have been proposed for making corrections in these dye images. Generally, these methods are characterizedby the fact that the mask is on a separate piece of film, and

of film as it ages, and problems of definition arising from lack of optical contact between original and mask, Newton rings, etc; It is desirable,

Thi creates problems of 5 Claims. (Cl. 95--2) therefore, to have the mask integral with the original. To accomplish this, it has been proposed to place an auxiliary emulsion layer within the pack in which the mask could be formed. While this gives a desirable result, it introduces complications into the structure and the preparation of the monopack material. Since the masking image is opposite in character to the one that it is desired to modify, emulsions with special properties have to be used.

To eliminate this complication, it was: proposed in British Patent 541,266 to utilize the residual silver-halides in the emulsion after the latent image has been processed to a dye image, and to convert the residual halides, after a proper exposure, into a silver mask. The procedure disclosed, to accomplish the formation of a mask, was to treat the film, after negative color development, in a bleach bath to convert the silver to silver chloride, to remove the silver chloride by treatment with ammonia or ammonium sulfite, then to expose the residual silver bromide to white light, and develop in an M. Q, developer that When processed in this yields a silver image. manner, there are formed silver images in each of the layers of the color film. This may be de-.

sirable under certain conditions, but for certain purposes the presence of a mask representing an image of the yellow dye pattern is harmful and undesirable. This was recognized by the British' patentee and he specifically states in his speci-1 fication that the bleach, to be used in effecting a conversion of the silver to silver chloride, must be of such a mild nature that it does not destroythe color sensitivities of the green and red sensitive layers. After treatment with such a mild,

bleach solution, it becomes possible to selectively expose the red and/or green sensitive layers, so that masking images may be formed only in these layers. v

The restriction to a bleach so mild that it does not destroy the color sensitivity of the green and,

red layers, severely limits the operator using the material and the manufacturer who makes it.

The patentee cites a number of sensitizing agents.

tical unless special sensitizers be used which are not so affected.

A further object is to provide a method for ob- I taining color corrected color negati-vema-teri'als wherein the color correction is integrally bound with the dye images,

Other objects and advantage of this invention will be apparent by reference to the foregoing specification, in which its preferred details and embodiments are described.

The foregoing objects are accomplished by fixing an exposed and developed photographic color negative film for a period of time ranging from /2 to 2 minutes, in a bath consisting of the following composition:

Ammonium or sodium thiosulfate grams 100 Sodium sulfate do 100 Water to make liter '1 All of the silver-halides remaining in'the uppermost (blue sensitive) layer are removed, leaving intact the'silver-halides in the other two layers. The sodium sulfate reduces the penetration of thethiosulfate and limits its action to the uppermost'layer. The fixed film is washed in water followed by a bleaching treatment, which converts the metallic silver in allthree layers'to silver chloride. Thesilver chloride thus formed is'then removed by bathing the bleached film in a saturated aqueous solution of ammonium, potassium, or sodium sulfite, ammonium chloride, ammonia or other'inorganic agent that difierentially removes silver chloride from a mixture of silver-halides. The processing of the film up to this point must be efiectuated in complete darkness, after which a yellow safelight may be employed.

The silver-halide remaining in the film has considerable sensitivity to blue light, though practically none to green or red light. By exposing the film for one minute to thelight of a 500 watt lamp, at a distance of several feet, the exposure being made either through the back or 'throughthe front, the silver-halides within the magenta and cyan layers becomedevelopable by means of a black andwhitedeveloper into masking silver images whose gradation is controlled by the degree of final development given, The overall density of the masking images is controlled by the length of the-exposure given the film,-j-ust prior todevelopment, which must, of course, be carried out in darkness-though yellow safelight illumination is permitted.

The procedure as outlined above comprises the following steps:

1. Exposure of the color negative film.

:2. Development of the latent images with a color developer.

3. Continued development of vthe film with a sulfite-containing black and white developer to achieve gamma infinity in all three layers. Although the continued black and white development may be optional, its inclusion, however, is desirable since it controls the quality of the final masking image.

4. Fixation by controlled diffusion of the residual halides in the top or blue sensitive layer of the film.

Conversion of all the silver negative images and any other silver such as thecolloidalsilver that may be present in the yellow filter and anti- 4 halation layers, into silver chloride by any bleach bath which does not impair the dye images already present.

6. Differential removal of silver chloride,

7. Exposure of the film to a controlled quantity of white light.

8. Development of the masking images by means of a normal black and white developer containing sufficient amounts of an alkali sulfite to preventthe formation of stain.

9. Fixation of'unused silver bromide.

10. Washing and drying.

It is also possible to effect a non-color selective masking image 'in'the cyan and magenta layers by meansother than that of exposure and development. For example, after the completion of Step 4, in the above procedure, the film can be bathed with a 1% aqueous solution of potassium or sodium iodide. This solution converts the residual silver-halides in the green and red sensitive layers into silver iodide, which will act as a mask. To achieve a more opaque image, the iodide bath may be replaced by a sulfide bath of the type used to formsilver sulfide images,such as a 1% solution of sodium sulfide. After conversion to iodide or sulfide, the film is treated with a solution or solutions that will convert the silver present in the negative, filter, or anti-halation layer, to a form which is soluble in hypo, so that salts like silver ferrocyanide, silver chloride or bromide, can be readily removed before any action on the iodide or sulfide becomes evident. A bleach bath such as:

Potassium ferricyanide ;'grams 40 Sodium bromide e do Water to make liter 1 will convert the silver to silver bromide without affecting either silver iodide or silver sulfide to any appreciable extent.

The alternative procedure as outlinedabove,

Example I A multi-layer photographic color film such as prepared according to United States Patents 2,179,228; 2,179,239; 2,186,849; 2,220,187; and 2,357,388, was exposed to a colored object and then developed for 15 minutes in a color developer of the following composition:

Diethyl amino aniline "grams 1.5 2 Amino 5 diethylaminotoluene mono I-Icl gram 1.0 Sodium sulfite do 0.5 Sodium carbonate grams 67.5 Potassium bromide do 2.5 Hydroxylamine HCl gram 0.5 Water to make liter 1 This development resulted in the formation of negative silver and color images at the exposed portions of the multi-layer film. The color developed: "film: was "then i shortestoppe-dfl in. a....1 %-v solution of acetic acid containing 11%. sodium acetate, washed for l0.minutes,wandl thenifixed for 1 minutes inta solutionof.theuiollowing.

By this fixing treatment. the. residual silver-- halides. inthe uppermost; blue sensitive layer were removed. The silver-halides the remaining layerswerenot. materially affected. In this fixinggbaththeiunction of the sulfate; istoprevent. the rapid diffusion .of the fixing bathintothe depth of thefilm. Any-otheragent, suchas:a1-- cohol, glycerin, sugar, etc, which. function inlike manner, can beused.

The fixed film was then; washed toremove excess. fixing; bath and. all. the. metalliasilver. in all. the layers, wasrcon-verted into silver; chloride by bathing in. asbath. of; thefollcwing composition:

Potassium ferricyanide grams 50 Sodium chloride -d'o- 50 Water to make liter 1 Thableached. film was washed in running wator for 5 minutes and the silver chloride formed in. the bleaching bath was removed by bathing in a. concentrated solution of sodium sulfite. The concentration normally required may vary from to saturation. Thepreferred concentration ofthesodiumsulfite, however,,is

At this, point the film contained a dyedmage in each of the 3, emulsion layers. In the cyan and magenta, layers there were alsopresent, besides the. negative dyeimages, positive silver-halide images other than of silver chloride. The silverhalide images in the latter layers cannot be developedunlessexposed to. light prior to. development.

The treated. film was washed in running water for several minutes and exposed to the light of a 500 watt lamp at adistance of 5. feet,.for, a, pcriodof 1 minutes The exposed film was developed in a hour-staining, black and whitedeveloper of thefollowing. composition:

Hydroquinone -gramsn 50' Sodium sulfite do Sodium carbonate do 25 Potassium bromide do r '2 Water to make "liter" 1 The developedfilm wasthen washed, fixed,..and dried in anormal manner.

During the black and white development the exposed silver-halides present in the cyan and magenta layers were reduced. to :metallic. silver thereby forming in each such layer a neutral tone masking image composed of metallic silver .to provideforcolor correctionin printing.

Example II Example I was repeated with the exception that after color development, the film was further developed in a non-staining black and white developer such as: I

Pyrogallic acid grams 5 Sodium sulfite do 80 Sodium carbonate do 10 Potassium bromide do 2 Water to make liter 1 ornany other; known non-staining black and white developer.. This development was carriedjonztd gamma infinity (the-highest obtainablecontrast; of a film) so thatall exposed; silver-halidegrains.

were developed.

The colored andblack and white developed film.

was then differentially fixed and processed through to completion in .the manner. set forth in Example I. This. procedure hasthe advantage over the .procedurein Example I inthat itxremoves all danger of having a. residual, negative silver image developed in the final or masking.

development, since all. silver-halide unexposed; inv

the first exposure, is exposed and. convertedxto metallic. silver thereby.

Example III Example I was repeatedup to and including the differential fixation of the image layers following color development. Thev film was washed in running water for 10. minutes, andthen subjected to the action of a 1% solution of potassium iodide, for a period of 10 minutes. In this treatment, the positive silver-halide images, present, in the cyan and magenta layers, were converted into silver iodide, which is stable and non-sensitive to the actionof light.

All the metallic silver, present in the various layers, was then converted into a silver salt, such as silver ferrocyanide, by the. action of a 10% solution of potassium ferricyanide. Instead ofemploying aqueous solutions of potassium ferricyanide, as the oxidizing agents, othersolutions of the commonly known oxidizingagent which convert the silver to a silver salt other than sil-- ver iodide, may be used, such as, for example, ferric chloride, copper sulfate in the presenceof bromide or chloride ions, and the like. The bleached film was washedin running water for several minutes and; treated with a normal fixing bath for 5 minutes, washed, and then dried.

In the normal fixing bath, the rate of fixation of the silver salts, such as silver chloride, silver bromide, silver ferrocyanide, and the like, is so much greater than the dissolution of silver iodide that to all intents and purposes, the action can be considered as affecting only the silver chloride, silver bromide andsilver ferricyamde, thus leaving the silver iodide image substantially unimpaired.

By this means, the silver iodide positive images, in the cyanand magenta layers, serve as masking images in the same manner as the silver images of Examples I and II.

The procedure, of the foregoing example has the advantage in that it cuts down the number of processing steps and reduces the time of proc.- essing.

Obviously, the practice of the present invention is, not to be limited to the processing of multilayer photographic color film of the type set forth in .the examples. Multi-layer photographic film such as prepared according to United States Patents 2,269,158.; 2,266,443; 2,272,191; 2,284,877; 2,289,803; 2,304,940; 2,311,020; 2,350,380; 72,397,- 864-5-6 and 7, and the like, can alsobe processed into color negatives containing masking images in accordance with the present invention. Various other modifications will occur to those skilled in'the art which, however, do not depart from the spirit and nature of this invention, and we do not intend to be limited in the patent granted except as required by the following claims.

We claim:

1. In the production of subtractively colored positives with correction printing masks, in-

aesaeae tegrally bound therein, for multilayer film having silver halide emulsion layers being respectively sensitized to the blue, green, and red regions of the spectrum and arranged so that the blue sensitive layer is the top layer with a yellow colloidal silver filter layer between the top blue layer and middle green layer, said sensitized layers containing color formers capable of producing dye images complementary in color to the one for which the layer is sensitized, by exposing the said multilayer film to a colored object and color developing the same, the improvement which comprises developing all layers of the said color developed film by a single development in a developer incapable of coupling with the color former in the layers for a time sufficient to bring the development to gamma infinity, selectively fixing the residual silver halides in the blue sensitive layer, bleaching the metallic silver in all layers including the filter layer to silver chloride at the same time so as to destroy the green and red sensitivities of the middle and lower layers, removing the silver chloride thus formed, exposing the residual silver halides in the green and red sensitive layers to white light, and developing the thus exposed silver halides in a black and white developer and removing the residual silver halides by fixing.

2. In the production of subtractively colored positives with correction printing masks, integrally bound therein, for multilayer film having silver halide emulsion layers being respectively sensitized to the blue, green, and red regions of the spectrum and arranged so that the blue sensitive layer is the top layer with a yellow colloidal silver filter layer between the top blue layer and middle green layer, said sensitized layers containing color formers capable of producing dye images complementary in color to the one for which the layer is sensitized, by exposing the said multilayer film to a colored object and color developing the same, the improvement which comprises developing all layers of the said color developed film by a single development in a developer incapable of coupling with the color former in the layers for a time sufficient to bring the development to gamma infinity, selectively fixing the residual silver halides in the top blue sensitive layer with an aqueous solution containing hypo and a member selected from the class consisting of alkali sulfates, water miscible alcohols, sugar and glycerin, bleaching the metallic silver in all layers including the filter layer to silver chloride with an aqueous solution containing sodium chloride and an oxidizing agent so as to destroy the green and red sensitivities of the middle and lower layers, removing the silver chloride thus formed with a solvent for said silver chlorides selected from the class consisting of alkali sulfite, ammonium chloride, and ammonia, exposing the residual silver halides in the green and red sensitive layers to white light and developing the exposed silver halides in a black and White developer to produce positive silver images of neutral tone in the green and red sensitive layers, and removing the residual silver halide by fixing.

3. In the production of subtractively colored positives with correction printing masks, integrally bound therein, for multilayer film having silver halide emulsion layers being respectively sensitized to the blue, green, and red regions of the spectrum and arranged so that the blue sensitive layer is the top layer with a yellow colloidal silver filter layer between the top blue layer and middle green layer, said sensitized layers containing color formers capable of producing dye images complementary in color to the one for which the layer is sensitized, by exposing the said multilayer film to a colored object and color developing the same, the improvement which comprises developing all layers of the said color developed film by a single development in a developer incapable of coupling with the color former in the layers for a time sufiicient to bring the development of gamma infinity, selectively fixing the residual silver halides in the top blue sensitive layer with an aqueous solution containing hypo and sodium sulfate, bleaching the metallic silver in all layers including the filter layer to silver chloride at the same time so as to destroy the green and red sensitivities of the middle and lower layers with an aqueous solution consisting of sodium chloride and potassium ferricyanide, removing the silver chloride thus formed with an aqueous solution of sodium sulfite, exposing the residual silver halides in the green and red sensitive layers to white light and developing the exposed silver halides in a black and white developer to produce positive images of neutral tone in the magenta and cyan layers and removing the residual silver halide by fixing.

4. In the production of subtractively colored positives with correction printing masks, integrally bound therein, for multilayer film having silver halide emulsion layers being respectively sensitized to the blue, green, and red regions of the spectrum and arranged so that the blue sensitive layer is the top layer with a yellow colloidal silver filter layer between the top blue layer and middle green layer, said sensitized layers containing color formers capable of producing dye images complementary in color to the one for which the layer is sensitized, by exposing the said multilayer film to a colored object and color developing the same, the improvement which comprises developing all layers of the said color developed film by a single development in a developer incapable of coupling with the color former in the layers for a time sufficient to bring the development to gamma infinity, selectively fixing the residual silver halides in the top blue sensitive layer with an aqueous solution containing hypo and a member selected from the class consisting of alkali sulfates, water miscible alcohols, sugar and glycerin, bleaching the metallic silver in all the layers including the filter layer to silver chloride at the same time to destroy the green and red sensitivities of the middle and lower layers with an aqueous solution containing sodium chloride and an oxidizing agent, removing the silver chloride with a solvent for said silver chloride selected from the class consisting of alkali sulfite, ammonium chloride, and ammonia, exposing the residual silver halides in the green and red sensitive layers to white light, developing the exposed silver halides in a black and white developer to produce positive metallic silver images in the magenta and cyan layers, and 1tlllien fixing, washing and drying the developed 5. In the production of subtractively colored positives with correction printing masks, integrally bound therein, for multilayer film having silver halide emulsion layers being respectively sensitized to the blue, green, and red regions of the spectrum and arranged so that the blue sens tive layer is the top layer with a yellow colloidal silver filter layer between the top blue layer and the middle green layer, said sensitized layers containing color formers capable of producing dye images complementary in color to the one for which the layer is sensitized, by exposing the said multilayer film to a colored object and color developing the same, the improvement which comprises developing all layers of the said color developed film by a single development in a develuper incapable of coupling with the color former in the layers for a time sufiicient to bring the development to gamma infinity, selectively fixing the residual silver halides in the top blue sensitive layer with an aqueous solution containing hypo and a member selected from the class consisting of alkali sulfates, Water miscible alcohols, sugar and glycerin, bleaching the metallic silver in all the layers including the filter layer to silver chloride at the same time to destroy the green and red sensitivities of the middle and lower layers with an aqueous solution containing sodium chloride and an oxidizing agent, difierentially removing the silver chloride with a solvent for said silver chloride selected from the class consisting of alkali sulfite, ammonium chloride,

and ammonia, exposing the residual silver halides in the green and red sensitive layers to white light, developing the exposed silver halides in a black and white developer containing sufiicient amounts of sulfite to produce positive metallic silver images in the magenta and cyan layers, and then fixing, washing and drying the developed film.

HAROLD C. HARS H. JOSEPH S. FRIEDMAN.

References Cited in the file of this patent UNITED STATES PATENTS a Number Name Date 2,059,884 Mannes et al Nov. 3, 1936 2,059,887 Mannes et a1 Nov. 3, 1936 2,340,656 Gaspar Feb. 1, 1944 2,357,388 Duerr et a1. Sept. 5, 1944 FOREIGN PATENTS Number Country Date 501,040 Great Britain 1939 541,266 Great Britain Nov. 20, 1941 

1. IN THE PRODUCTION OF SUBTRACTIVELY COLORED POSITIVES WITH CORRECTION PRINTING MASKS INTEGRALLY BOUND THEREIN, FOR MULTILAYER FILM HAVING SILVER HALIDE EMULSION LAYERS BEING RESPECTIVELY SENSITIZED TO THE BLUE, GREEN, AND RED REGIONS OF THE SPECTRUM AND ARRANGED SO THAT THE BLUE SENSITIVE LAYER IS THE TOP LAYER WITH A YELLOW COLLOIDAL SILVER FILTER LAYER BETWEEN THE TOP BLUE LAYER AND MIDDLE GREEN LAYER, SAID SENSITIZED LAYERS CONTAINING COLOR FORMERS CAPABLE OF PRODUCING DYE IMAGES COMPLEMENTARY IN COLOR TO THE ONE FOR WHICH THE LAYER IS SENSITIZED, BY EXPOSING THE SAID MULTILAYER FILM TO A COLORED OBJECT AND COLOR DEVELOPING THE SAME, THE IMPROVEMENT WHICH COMPRISES DEVELOPING ALL LAYERS OF THE SAID COLOR DEVELOPED FILM BY A SINGLE DEVELOPMENT IN A DEVELOPER INCAPABLE OF COUPLING WITH THE COLOR FORMER IN THE LAYERS FOR A TIME SUFFICIENT TO BRING THE DEVELOPMENT TO GAMMA INFINITY, SELECTIVELY FIXING THE RESIDUAL SILVER HALIDES IN THE BLUE SENSITIVE LAYER, BLEACHING THE METALLIC SILVER IN ALL LAYERS INCLUDING THE FILTER LAYER TO SILVER CHLORIDE AT THE SAME TIME SO AS TO DESTROY THE GREEN AND RED SENSITIVITIES OF THE MIDDLE AND LOWER LAYERS, REMOVING THE SILVER CHLORIDE THUS FORMED, EXPOSING THE RESIDUAL SILVER HALIDES IN THE GREEN AND RED SENSITIVE LAYERS TO WHITE LIGHT, AND DEVELOPING THE THUS EXPOSED SILVER HALIDES IN A BLACK AND WHITE DEVELOPER AND REMOVING THE RESIDUAL SILVER HALIDES BY FIXING. 